Coaxial cables are widely used to carry high frequency electrical signals. Coaxial cables enjoy a relatively high bandwidth, low signal losses, are mechanically robust, and are relatively low cost. One particularly advantageous use of a coaxial cable is for connecting electronics at a cellular or wireless base station to an antenna mounted at the top of a nearby antenna tower. For example, the transmitter located in an equipment shelter may be connected to a transmit antenna supported by the antenna tower. Similarly, the receiver is also connected to its associated receiver antenna by a coaxial cable path.
A typical installation includes a relatively large diameter cable extending between the equipment shelter and the top of the antenna tower to thereby reduce signal losses. For example, CommScope, Inc. of Hickory, N.C, and the assignee of the present invention, offers its CellReach® coaxial cable for such applications. The cable includes a smooth wall outer conductor that provides superior performance to other cable types. The smooth outer wall construction also provides additional ease of attaching connector portions to the cable ends in comparison to other coaxial cable types, such as including corrugated outer conductors, for example.
A typical coaxial cable connector for such a coaxial cable includes a tubular housing or body to make electrical connection to the cable outer conductor and a center contact to make electrical connection to the inner conductor of the coaxial cable. The center contact may include a tubular rearward end to receive the inner conductor of the coaxial cable. An insulator assembly supports the center contact concentrically within the housing. The insulator assembly may typically include multiple cooperating parts.
A typical connector may also include a gripping member or ferrule that is positioned onto the end of the outer conductor and adjacent the outer insulating jacket portion of the coaxial cable. The ferrule is axially advanced into the housing as a back nut is tightened onto the rearward end of the housing. One or more O-rings may be provided to environmentally seal the connector to prevent the ingress of water, for example, into the connector.
Representative patents directed to coaxial cable connectors include U.S. Pat. No. 6,396,367 B1 to Rosenberger; U.S. Pat. No. 6,024,609 to Kooiman et al.; U.S. Pat. No. 6,607,398 B2 to Henningsen; and U.S. Pat. No. 6,217,380 B1 to Nelson et al. The entire contents of each of these patents are incorporated herein by reference.
U.S. Pat. No. 7,011,546 to Vaccaro, assigned to the assignee of the present invention and incorporated herein by reference, discloses a connector, having significant advantages over the prior art. The connector includes a housing, a back nut threadingly engaging a rearward end of the connector housing, a ferrule gripping and advancing an end of the coaxial cable into the connector housing as the back nut is tightened, and an insulator member positioned within a medial portion of the connector housing. In addition, the insulator member has a bore extending therethrough and includes a forward portion, a rearward portion, a ring portion connecting the forward and rearward portions together, and a tubular outer conductor support portion extending rearwardly from the rearward portion for supporting an interior surface of the outer conductor of the end of the coaxial cable. The ring portion may have a reduced strength portion defining a crush zone to facilitate movement of the rearward portion toward the forward portion as the back nut is tightened onto the connector housing.
CommScope has made another connector similar to the Vaccaro patent wherein the insulator member 5 is tuned to match impedances between the connector and the cable end. More particularly, as understood with reference to FIG. 1, the prior art insulator member 5 includes a forward portion 7 including a pair of longitudinal passageways therethrough 8a, 8b, for impedance matching. The insulator member 5 also comprises a tubular outer conductor support portion including a sidewall 6 initially formed to a have an inner diameter d1. In subsequent machining steps, two additional enlarged diameters d2, d3 are formed in the sidewall 6 to tune the impedance. In other words, after the initial molding to form the insulator member 5, the two enlarged diameters d2, d3 are created by additional machining steps. These extra manufacturing steps may increase the cost and/or complexity of the manufacturing.